stirred mills

Abstract

The invention relates to a stirred mill having a grinding chamber and a grinding rotor which, in operation, forms a rotating boundary wall of the grinding chamber. The grinding rotor causes grinding bodies to perform a grinding motion in the grinding chamber. Furthermore, there is a gap tube for extracting ground material while separating the grinding bodies.

Description

Technical Field

[0001] This invention relates to a stirred mill (Rührwerksmühle) and a gap tube (Spaltrohr). Background Technology

[0002] Stirred mills are used for deagglomeration of solids or to reduce the particle size in suspensions or dispersions to be milled, ranging from hundreds of micrometers to a few nanometers.

[0003] The following is based on Figure 1 To explain the process that occurs inside the stirred mill.

[0004] exist Figure 1 The figure schematically illustrates a stirred mill 1 with a horizontal grinding rotor 3 (also commonly referred to as a stirring shaft). The grinding media (Mahlkörper) located in the grinding container 13 are not shown in the figure; they are typically implemented as steel balls or ceramic balls.

[0005] When the stirred mill 1 is in operation, the material to be ground is pumped into or through the grinding chamber 2 formed by the grinding container 13 via the inlet 14 of the stirred mill 1.

[0006] The rotational motion of the grinding rotor 3 causes the stirring element 4 (which is also commonly referred to as the grinding disc) to rotate, which is connected to the grinding rotor 3 in a torsion-resistant manner.

[0007] To generate rotational motion, the grinding rotor 3 can be driven by a motor, for example, via a belt drive (not shown). The drive unit for the stirred mill 1 is usually located in the housing adjacent to the grinding container 13.

[0008] The rotation of the stirring element 4 causes the grinding media (located near the stirring element 4) in the grinding chamber 2 to move circumferentially along with the grinding container 13. In the intermediate region between every two stirring elements 4, the moving grinding media immediately flow back towards the grinding rotor 3 upon reaching its apex position. Therefore, there is a cyclic motion of the grinding media between every two stirring elements 4. To achieve the finest possible particle size in the micrometer or nanometer range, an ideal grinding media with dimensions between 30 µm and 6 mm is used.

[0009] The movement of the grinding media causes collisions between the solids in the material suspension being pumped through the grinding chamber 2 and the grinding media. These collisions result in the fragmentation of finer solid particles in the material suspension, so that the solids reaching the outlet 15 of the stirred mill 1 are ultimately significantly smaller than those fed in at the inlet 14. Here, the maximum achievable pulverization directly depends on: the size of the grinding media, the energy of the introduced stirring element 4, and the residence time of the material suspension in the grinding chamber 2.

[0010] To ensure that no grinding media is extracted from the grinding chamber 2, a separation system 6 is provided before the outlet 15 (through which the ground material is extracted). This separation system may take the form of a screen, filter, or gap tube (in the following text, the term "screen" shall cover all types of separation systems).

[0011] To prevent the grinding media from leaving the grinding container, a screen is typically used. The slit size of this screen is approximately 1.5 to 4 times smaller than the particle size of the grinding media.

[0012] The problem with this approach is that reducing the slit size while keeping the total screen diameter constant leads to a decrease in the total free flow area on the screen. While theoretically the number of slits could be increased to maintain the same free flow area, it's practically impossible to increase the number of slits while simultaneously reducing the slit size to keep the total flow area constant (due to strength requirements). This reduction in the total free flow area on the screen ultimately increases the flow velocity of the ground material through the slits. This, in turn, increases the suction or force effect of the grinding media in the screen area along the slit direction. Consequently, the grinding media are pressed against the screen and eventually block the screen openings or slits. This ultimately results in insufficient or no ground material flowing through the screen from the grinding chamber, necessitating screen cleaning. In such cases, the screen must be disassembled, incurring maintenance costs and increasing downtime of the stirred mill.

[0013] exist Figures 2 to 10 The diagram shows how separation systems implemented as gap tubes have been used internally so far, but it has come to the conclusion that such separation systems need improvement.

[0014] Figures 2 to 5 A radial gap tube is shown. The gap components 7 are helically wound around the support 16, such that the gaps 8 located between the gap components 7 also extend helically around the longitudinal axis of the gap tube 6. As shown in... Figure 5As can be seen, the grinding body 5 moves along the direction of the gap 8 together with the material being ground. A particular drawback of this radial gap tube is that, when the stirred mill is operating, the grinding body 5 in the region of the gap tube 6 moves circumferentially around the longitudinal axis of the gap tube 6 in any way. Therefore, the grinding body 5 moves approximately parallel to the gap 8. This makes it particularly easy for the grinding body 5 to enter the gap 8 or enter the inlet region of the gap 8 and become blocked.

[0015] Due to the aforementioned problems with radial gap tubes, a method such as... was used in internal experiments. Figures 6 to 9 The axial clearance tube shown is illustrated. The clearance component 7 (with a gap between them) is arranged parallel to the longitudinal axis of the clearance tube 6 on the support 16. As can be seen from... Figure 9 As can be seen, the grinding body 5 rotating in the grinding chamber does not move parallel to or approximately parallel to the longitudinal direction of the gap 8, but rather rolls or slides on it at an angle of approximately 90° to the longitudinal direction of the gap. This results in the grinding body 5 initially not blocking the gap 8 or its inlet region. However, for this type of axial gap tube, when the flow velocity at the gap 8 exceeds a certain level, the grinding body 5 will continuously accumulate in the gap 8 or its inlet region. Summary of the Invention

[0016] In view of the above problems, the object of the present invention is to provide a stirred mill in which the grinding media can be reliably separated from the grinding material, and ideally even when the flow rate in the gap tube region is increased.

[0017] According to the present invention, the above problems are solved by means of a stirred mill.

[0018] Therefore, the problem is solved by means of a stirred mill having a grinding chamber, a grinding rotor and grinding media, and a gap tube. During operation, the grinding rotor forms a rotating boundary wall of the grinding chamber, and causes the grinding media to undergo grinding motion within the grinding chamber. The gap tube is used to extract the ground material while separating the grinding media. This stirred mill is characterized by an axial gap tube. Here, circumferentially adjacent gap components of the axial gap tube form a gap between its two longitudinal edges, this gap having a disruptive geometry. This disruptive geometry causes the grinding media, which rolls or slides circumferentially along the outer surface of the gap tube, to be lifted from the outer circumferential surface as it passes through the gap. Here, the outer circumferential surface is defined by the gap components.

[0019] The material being ground leaves the stirred mill by passing through the gap in the gap tube into the interior of the gap tube and then flowing out of the stirred mill from there.

[0020] For this purpose, a gap tube is arranged in the outlet region of the stirred mill and has an opening at the end opposite to the stirred mill. The gap tube is closed at the end that extends into the stirred mill, or at least designed so that the grinding media cannot enter the interior of the gap tube from that end.

[0021] The function of the gap tube is to prevent the grinding media from leaving the stirred mill. Therefore, it functions as a screen. Here, the screen surface of the gap tube is formed by gap components. In this context, the screen surface means a surface with channels for a specific medium (here, the grinding material) to pass through, but these channels are not large enough to allow another medium (here, the grinding media) to pass through. Gap components are formed between portions of the gap tube, through which access to the hollow interior of the gap tube is possible. The gap components can be formed as strips, wires, or a single-piece hollow cylinder with multiple insertion gaps.

[0022] Compared with conventional gap tubes, the gap tube according to the present invention has the advantage of preventing or at least greatly limiting the obstruction of the gap or its inlet region by the grinding body.

[0023] To achieve this, the gap tube is fitted with one or more interference geometries on its outer peripheral surface. These interference geometries involve a portion of the gap tube that causes the grinding body, sliding along the outer peripheral surface of the gap tube, to move and rise from the outer peripheral surface from a position immediately preceding each gap. However, at this point, the grinding body is not braked or only braked to a very small extent. Therefore, the grinding body continues to rotate about the longitudinal axis of the gap tube. As a result, after the grinding body rises from the outer peripheral surface, the ground material flows below the grinding body (overflow). Here, according to boundary layer theory, in the boundary layer between the outer peripheral surface of the gap tube and the grinding body, the flowing ground material has a lower velocity than the ground material flowing across the opposite side of the grinding body. According to Bernoulli theory, this results in a negative pressure between the grinding body and the outer peripheral surface of the gap tube relative to the pressure on the side of the grinding body away from the gap tube. For this reason, the grinding media is pressed away from the outer peripheral surface of the gap tube. As the grinding media rotates, the movement of the grinding media away from the outer peripheral surface of the gap tube is also enhanced by the so-called Magnus-Effekt effect.

[0024] The design of the interference geometry can be achieved in different ways. For example, a ramp-shaped barrier can be placed on the outer peripheral surface of the gap tube immediately before each gap. For instance, when the axial gap tube is composed of rod-shaped gap components, these rod-shaped gap components have schanzenartig (skipping) lippes at their edges, that is, a kind of "spoiler," which the grinding media passes over during operation in the direction of the next gap. This lippe or spoiler is designed such that the grinding media impacting it is lifted from the outer peripheral surface immediately before the next gap.

[0025] The term “axial clearance tube” can be used in both a broad and narrow sense in this article.

[0026] In a broader sense, the term can refer to an axially helical clearance tube (Axialschraubenspalt-rohr). The clearance of this clearance tube extends helically, with a tangent angle T less than 45°, more preferably less than 30°, and ideally less than 20°, but in every case greater than 5°. Here, the term "tangent angle" refers to the smallest angle enclosed by the tangent to the longitudinal axis of the corresponding clearance and the longitudinal axis of the clearance tube when they are projected onto each other.

[0027] The term “axial clearance tube” is narrowly defined as a true “axial clearance tube” and therefore means that the clearance of the clearance tube extends parallel to or (in the sense defined above) at least approximately (by + / - 2° and smaller) or substantially parallel to the longitudinal axis of the clearance tube with respect to its longitudinal axis.

[0028] The “outer peripheral surface” of a gap tube refers to the sum of the surfaces of individual gap components that extend 360° around the longitudinal axis of the gap tube and are located away from the longitudinal axis of the gap tube.

[0029] It is also worth noting that it is best for each gap to be equipped with a corresponding interference geometry. However, this is not absolutely necessary in all cases. In some situations, if only a single gap is provided according to the invention, preferably those single gaps that are always arranged in the same way as conventional gaps, this may be a compromise.

[0030] The object of the present invention is also to manufacture a gap tube using a simplified method that is subject to wear to the least extent possible, which enables reliable separation of the grinding media from the grinding material and, ideally, maintains the necessary flow rate.

[0031] The above problems are solved by using a gap tube for a stirred mill. This gap tube is characterized in that it is an axial gap tube. The circumferentially adjacent gap components of the axial gap tube form a gap between their two longitudinal edges. This gap is equipped with a disturbance geometry that causes the grinding media, which rolls or slides circumferentially along the outer surface of the gap tube, to be lifted from the outer circumferential surface as it passes through the gap. Here, the outer circumferential surface is defined by the gap components.

[0032] In this form of the invention, the interference geometry is implemented in a specific way by forming a stepped gap between the two longitudinal edges of adjacent gap components. That is, the longitudinal edge of a gap component adjacent to the gap has a smaller radius than the longitudinal edge of another gap component adjacent to the same gap in the direction of movement of the grinding body. This means that the grinding body reaches each gap via its radially outer edge and subsequently traverses the gap, thus leaping a certain distance over the other radially inner edge of the same gap. In other words, it is through this method that the grinding body—flowing approximately circumferentially along the outer peripheral surface of the gap tube—is able to skip gaps from the surface of the gap component it is traversing to (or “jump” to) the next gap component, without immediately “landing” on the surface of the next gap component. Instead, the grinding body first approaches the surface of the next gap component, where it is overflowed and thus receives radially outward pulses.

[0033] These types of gap tubes, or stepped gap tubes, can be installed in stirred mills. Due to the scouring effect of the grinding media sliding along the outer circumferential surface of the gap tube, as described earlier, the downtime of stirred mills can be significantly reduced by installing such gap tubes. This is because, compared to conventional separation systems, these gap tubes require little or no cleaning.

[0034] The effectiveness or practicality of this invention can be further enhanced through a series of design approaches.

[0035] In a preferred embodiment, the gap component is a strip. The cross-section of the strip, associated with the axis of rotation of the gap tube, defines a surface structure that is fixed to the gap tube in an asymmetrical manner with respect to the axis of rotation.

[0036] Ideally, the strip is formed from wire. This is advantageous for manufacturing reasons. If the strip or gap component is made of wire, the gap tube can be manufactured in a relatively quick manner (as described below).

[0037] First, multiple connecting plates (Steges) are arranged or clamped in a circular pattern at uniform intervals. Ideally, these connecting plates are not composed of wires forming the gap components. Then, in the assembled state, the wires forming the gap components are wound around the connecting plates and soldered to them, with gaps existing between individual windings. This forms the structure described above... Figure 2 The geometry of the radial gap tube is described. The radial gap tube, formed in this way, is finally separated and unwound along its longitudinal axis, so that all the gap components lie in a single plane. Finally, the plane formed in this way is rotated 90°, wound again in a circular manner, and closed again, for example, by welding. The result is a gap tube with gaps extending parallel to the longitudinal axis.

[0038] Because the cross-sections of the gap components are arranged to be non-symmetrical about the longitudinal axis, it is easy to create the stepped gap described above between every two consecutive gap components. In this sense, the non-existent symmetry refers to the axial symmetry of the cross-section of each gap component with respect to the plane containing the longitudinal axis of the gap tube.

[0039] However, an attractive option is to choose a design in which the cross sections of every two opposing gap components are arranged point-symmetrically around the longitudinal axis.

[0040] The term "strip" preferably describes a geometry in which the length of the axis of rotation parallel to the gap tube is at least 10 times longer than the length in the circumferential direction, and preferably at least 15 times longer.

[0041] Ideally, the gap component is a strip whose cross-section about the axis of rotation of the gap tube becomes narrower in the radially inward direction (viewed in the circumferential direction).

[0042] Therefore, the gap width increases further from the narrowest point on the outer circumferential surface of the gap tube towards the interior of the gap tube. The advantage of this is that if the grinding media does get stuck in the gap in an undesirable way, the grinding media can be flushed out of the gap more easily, or the gap tube as a whole can be cleaned more easily.

[0043] The "radial inward" direction refers to the direction from the outer peripheral surface of the gap tube toward the interior of the gap tube.

[0044] The gap component is preferably a strip with a wedge-shaped cross-section about the longitudinal axis (and rotation axis) of the gap tube, and preferably a double wedge shape. Here, the base of the wedge, opposite the inner wedge tip, defines the outer peripheral surface.

[0045] Therefore, the wedge-shaped legs represent the walls of the gap. Preferably, the gap walls in the region directly adjacent to the outer peripheral surface have an angle between 68° and 85°. Starting from a certain gap depth, the wedge-shaped legs preferably have an angle between 60° and 80°. This creates a bend in the gap wall that widens the gap overall. Due to the greater material thickness in the region of the outer peripheral surface, higher strength of the gap component is achieved in this region. Simultaneously, the interior of the gap can be effectively cleaned.

[0046] The term "double wedge" describes a geometric structure derived from a trapezoid combined with a triangle, wherein the angle between the base of the triangle and its corresponding leg (hereinafter referred to as α) is not equal to the angle between the base of the trapezoid and its corresponding leg (hereinafter referred to as β). Preferably, angle α is less than angle β. Therefore, the "double wedge" preferably has at least one first wedge portion and one second wedge portion.

[0047] In another preferred embodiment, a perpendicular line passing through the inner tip of the wedge and perpendicular to the base of the wedge does not intersect the axis of rotation of the gap tube. Instead, the perpendicular line has a non-negligible distance from the axis of rotation. Ideally, this distance is at least twice the maximum circumferential width of the wedge, and more preferably at least four times it.

[0048] Therefore, the plane containing the bottom and the longitudinal axis of the gap tube is not orthogonal. As a result, the grinding body rolling or sliding on the outer peripheral surface forming the bottom will bounce across the gap between the two gap components. When the grinding body is above the gap, overflow will occur as described above.

[0049] Ideally, the gap tube is an axial gap tube, in which adjacent gap components in the circumferential direction form a stepped gap between their two longitudinal edges. A stepped gap in this sense means that the longitudinal edge of one gap component adjacent to the gap has a smaller radius than the longitudinal edge of another gap component adjacent to the same gap.

[0050] In such gap tubes, the grinding media sliding or flowing along the outer circumferential surface of the gap tube—once it reaches the gap—overflows. As described above, this causes the grinding media to be pushed away from the gap tube, rather than entering the gap.

[0051] This type of gap tube can replace the traditional separation system of the stirring shaft, so as to reduce the downtime of the stirred mill due to cleaning operations.

[0052] In addition, there is a separate requirement to protect the use of gap tubes in mills (preferably stirred mills) for discharging the ground material while separating the grinding media. Attached Figure Description

[0053] Figure 1 A prior art stirred mill is schematically shown, on which a gap tube according to the invention can be used.

[0054] Figure 2 An isometric view of a radial gap tube, which is not based on the invention, is shown.

[0055] Figure 3 It shows Figure 2 Side view of the radial clearance tube.

[0056] Figure 4 It shows Figure 2 A cross-sectional view of the radial clearance tube.

[0057] Figure 5 The grinding media in Figure 2 Movement in the region of the radial clearance tube shown.

[0058] Figure 6 An isometric view of an axial clearance tube, not according to the present invention, is shown.

[0059] Figure 7 It shows Figure 6 Side view of the axial clearance tube.

[0060] Figure 8 It shows Figure 6 A cross-sectional view of the axial clearance tube.

[0061] Figure 9 The grinding media in Figure 6 Movement in the region of the longitudinal gap tube not according to the invention.

[0062] Figure 10 An isometric view of a longitudinal stepped gap tube according to the present invention is shown.

[0063] Figure 11 The above is shown Figure 10 The image shows a side view of the longitudinal stepped gap tube according to the present invention.

[0064] Figure 12 The above is shown Figure 10 The cross-sectional view of the longitudinal stepped gap tube according to the present invention is shown.

[0065] Figure 13 The grinding media in Figure 10 Movement in the region of the gap tube according to the invention.

[0066] Figure 14 A variant of the invention in the form of an axially spiral gap tube is shown.

[0067] Figure 15A variant of the invention is shown in which the interference geometry is implemented differently, i.e. as strips that protrude radially from the surrounding environment, such as spoilers. Detailed Implementation

[0068] For example, according to Figures 10 to 13 The working method of the present invention has been explained. Figure 14 and 15 Variations of the invention are shown. For clarity, elements or regions that appear multiple times are given reference numerals only as examples.

[0069] In the assembled state, the gap tube 6 is arranged in... Figures 10 to 13 Also refer to the outlet area of ​​the stirred mill (not shown). Figure 1 The purpose is to allow the grinding material to leave the grinding chamber while preventing the grinding body 5 from leaving the grinding chamber. For this purpose, the gap tube 6 has multiple gaps 8 on its outer peripheral surface—which is jointly formed by the outer peripheral surface 11 of the gap component 7. Through these gaps 8, the grinding material flows into the interior of the gap tube 6 and out through an open end face of the gap tube 6. Here, the gaps 8 are so narrow that the grinding body 5 cannot, or is substantially unable to, pass through the gap, or has difficulty passing through the gap.

[0070] The gap tube 6 consists of two end parts 17, a gap component 7, and a circular support 16. The support 16 is used to hold the gap component 7 in place and, in particular, to improve its rigidity. The support is formed of a ring (ideally a metal ring).

[0071] To achieve a sufficiently strong connection between the support member 16 and the gap member 7, it is preferable to weld them together. The gap members 7 are arranged around the support member 16 at uniform spacing, and for this obviously preferred embodiment, each gap member 7 is provided with a gap 8 implemented as a stepped gap between the longitudinal edges 9 of two adjacent gap members 7.

[0072] One end face of the gap tube 6—which is opposite to the end face of the gap tube 6 through which the grinding material flows out—is preferably closed or at least covered in the assembled state, so that neither the grinding material nor the grinding body can flow through the end face.

[0073] The gap component 7 is made of a strip, the length of which extends in a direction parallel to the longitudinal axis of the gap tube 6 is at least ten times greater than its length extending in the circumferential direction of the gap tube 6. Ideally, the strip is made of wire or of a stretched or extruded metal material.

[0074] Here, the cross-sectional profile of the gap component 7 is wedge-shaped 10, preferably in a double-wedge form, consisting of two wedge-shaped portions 18 and 19. Wedge portion 19 is formed by a triangle, while wedge portion 18 is formed by a trapezoid. The legs of the wedge-shaped portions merge together, and at the transition point between the two wedge-shaped portions 18 and 19, the double wedge 10 has a bend. This bend occurs because the angle between the bottom 11 of the wedge 10 and the leg of the wedge portion 18 is greater than the angle between the bottom 11 and the leg of the wedge portion 19.

[0075] To prevent the grinding media from wedging into and blocking the gap, gap 8 is implemented as a stepped gap. How these gaps are formed and their function will depend on... Figure 12 and 13 To illustrate.

[0076] In the assembled state, the gap component 7 is arranged around the longitudinal axis of the gap tube 6, such that the perpendicular line from the wedge tip 12 on the bottom 11 does not pass through the longitudinal axis of the gap tube 6. Ideally, the two edges forming the same gap have different radii, but the triangular portion (Delta) is preferably less than four grinding body diameters and ideally less than two grinding body diameters.

[0077] In other words, it is preferable that individual gap components are fixed together like a series of dominoes tilting in the circumferential direction, typically by welding, thereby forming a stepped gap tube, see [link to relevant documentation]. Figure 12 .

[0078] Therefore, the longitudinal edge 9 of the first gap member 7—relative to the longitudinal edge 9 of the next gap member 7 facing it—is arranged with a larger radius around the longitudinal axis of the gap tube 6. Thus, the gap 8 between every two gap members 7 is achieved as a stepped gap. This positioning method allows for better control in terms of manufacturing technology. From a wear perspective, this is also very advantageous overall, because the cross-section of the gap member is thick throughout, and therefore wear-resistant, significantly stronger than the case where the "spoiler" or "guide boss" appears as a naturally finer protrusion in cross-section.

[0079] Therefore, the grinding body 5, which rolls or slides along the first gap member 7, is overflowed by the grinding material located in that area as it passes through the longitudinal edge 9. Because the grinding material between the grinding body 5 and the gap member 7 flows more slowly—compared to the grinding material on the opposite side of the grinding body 5—a negative pressure is generated in the area between the grinding body 5 and the next gap member 7 according to Bernoulli's principle. Thus, the grinding body 5 is pressed away from the gap tube 6. This prevents the gap 8 from being blocked by the grinding body.

[0080] As previously stated, according to the present invention, the term "axial clearance tube" has both a narrow and a broad meaning. In a narrow sense, it only covers clearance tubes whose clearance has a longitudinal axis that is parallel (at least substantially parallel to or even completely parallel to, except for tolerance deviations) to the central longitudinal axis L of the clearance tube.

[0081] In a broader sense, this now also includes gap tubes whose gaps extend in a spiral shape, and are therefore also called axially spiral gap tubes. Figure 14 This illustrates the point. The gap component extends in a spiral shape, just like the gap itself, but as mentioned earlier, the gap component itself is inclined.

[0082] It should be noted that the axial clearance tube according to the invention may optionally also have adjacent clearance components 7, which form a gap 8 between their two longitudinal edges 9, but which form a different type of interference geometry. In this example, the interference geometry is formed by a protrusion or a spoiler. The grinding body impacts the protrusion or spoiler and rolls or slides circumferentially along the outer peripheral surface 11 of the clearance tube 6 so as to be ejected in a radially outward direction, thereby preventing the grinding body from entering the gap. According to the invention, this solution is feasible, but in some applications, the strong impact of the grinding body can lead to a significant increase in wear.

[0083] List of reference numerals

[0084] 1. Stirred mill

[0085] 2 Grinding chamber

[0086] 3. Grinding rotor

[0087] 4. Grinding disc / stirring element

[0088] 5. Grinding body

[0089] 6. Gap tube / Axial gap tube / Screen / Separation system

[0090] 7. Gap components / strips

[0091] 8-Gap / Stepped Gap

[0092] 9. Longitudinal edge of the gap component

[0093] 10 wedge-shaped

[0094] 11. Bottom / outer peripheral surface of the clearance component

[0095] 12 wedge-shaped tips

[0096] 13 Grinding containers

[0097] 14. Inlet of the grinding container

[0098] 15. Outlet of the grinding container

[0099] 16. Supporting members for gap components

[0100] 17. End components of the gap tube

[0101] 18 First wedge-shaped part

[0102] 19 Second wedge-shaped section

[0103] 20 Protrusions / Spoilers

[0104] The central longitudinal axis of the L-gap tube

[0105] T is the tangent angle between the central longitudinal axis of the gap tube and the central longitudinal axis of the axial gap.

Claims

1. A stirred mill (1) comprising: a grinding chamber (2); a grinding rotor (3) forming a rotating boundary wall of the grinding chamber (2) during operation; a grinding body (5) causing the grinding rotor (3) to perform grinding motion in the grinding chamber (2); and a gap tube (6) for extracting the ground material while separating the grinding body (5), characterized in that, The gap tube (6) is an axial gap tube, and the adjacent gap components (7) of the gap tube (6) form a gap (8) between its two longitudinal edges (9). The gap (8) has an interference geometry, which is used to allow a grinding body (5) that rolls or slides along the outer peripheral surface (11) of the gap tube (6) in the circumferential direction to be lifted from the outer peripheral surface (11) as the grinding body (5) passes through the gap (8). The outer peripheral surface (11) is defined by the gap components (7).

2. The stirred mill (1) according to claim 1, characterized in that, The adjacent gap components (7) of the gap tube (6) form a stepped gap (8) between its two longitudinal edges (9), and the longitudinal edge (9) of the gap component (7) adjacent to the gap (8) has a larger radius than the longitudinal edge (9) of the next gap component (7) adjacent to the same gap (8) in the direction of rolling or sliding of the grinding body (5).

3. The stirred mill (1) according to claim 1 or 2, characterized in that, The gap component (7) is a strip, and the strip cross section related to the rotation axis of the gap tube (6) defines a surface structure, which is fixed to the gap tube (6) such that there is no mirror symmetry about the rotation axis of the gap tube (6) and / or about any plane of the gap tube (6), wherein the plane passes through the rotation axis of the gap tube (6).

4. The stirred mill (1) according to claim 1 or 2, characterized in that, The gap component (7) is a strip, and the cross section of the strip, which is related to the rotation axis of the gap tube (6), becomes narrower in the radially inward direction when viewed in the circumferential direction.

5. The stirred mill (1) according to claim 1 or 2, characterized in that, The gap component (7) is a strip, and the cross section of the strip related to the rotation axis of the gap tube (6) is wedge-shaped (10), and the bottom of the wedge, which is opposite to its inner wedge tip (12), defines the outer peripheral surface (11).

6. The stirred mill (1) according to claim 5, characterized in that, The strip cross section associated with the rotation axis of the gap tube (6) is a double wedge shape with at least two wedge-shaped portions (18, 19).

7. A gap tube (6) for a stirred mill, characterized in that, The gap tube (6) is an axial gap tube, and the adjacent gap components (7) of the gap tube (6) form a gap (8) between its two longitudinal edges (9). The gap (8) has a disturbance geometry that allows a grinding body (5) rolling or sliding along the outer peripheral surface (11) of the gap tube (6) in the circumferential direction to be lifted from the outer peripheral surface (11) as the grinding body (5) passes through the gap (8). The outer peripheral surface (11) is defined by the gap components (7).

8. The gap tube (6) for a stirred mill according to claim 7, characterized in that, The adjacent gap components (7) of the gap tube (6) form a stepped gap (8) between its two longitudinal edges (9), and the longitudinal edge (9) of the gap component (7) adjacent to the gap (8) has a larger radius than the longitudinal edge (9) of the next gap component (7) adjacent to the same gap (8) in the direction of rolling or sliding of the grinding body (5).

9. A gap tube (6) for use in a stirred mill (1) according to any one of claims 1 to 6, characterized in that, The gap tube (6) is an axial gap tube, and the adjacent gap components (7) of the gap tube (6) form a gap (8) between its two longitudinal edges (9). The gap (8) has a disturbance geometry that allows a grinding body (5) rolling or sliding along the outer peripheral surface (11) of the gap tube (6) in the circumferential direction to be lifted from the outer peripheral surface (11) as the grinding body (5) passes through the gap (8). The outer peripheral surface (11) is defined by the gap components (7).

10. The gap tube (6) for a stirred mill (1) according to claim 9, characterized in that, The adjacent gap components (7) of the gap tube (6) form a stepped gap (8) between its two longitudinal edges (9), and the longitudinal edge (9) of the gap component (7) adjacent to the gap (8) has a larger radius than the longitudinal edge (9) of the next gap component (7) adjacent to the same gap (8) in the direction of rolling or sliding of the grinding body (5).

11. Use of the gap tube (6) according to any one of claims 7 to 10 in a mill, the gap tube (6) being used to extract the milled material while separating the milling body (5).

12. The use as described in claim 11, characterized in that, The mill is a stirred mill (1).

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